1. Field of the Invention
The present invention relates to a gas generator for an air bag used in an air bag system-installed in a vehicle.
2. Description of the Related Art
A gas generator for an air bag preferably inflates the air bag as the amount of gas generated is varied over time, in order to reduce the impact of air bag inflation on the passenger while providing a sufficient restraining performance.
To inflate an air bag in this fashion, a known conventional gas generator employs two igniters to burn individual gas generating agents at different times. However, the structure of this gas generator is complicated, and the use of two igniters makes assembly difficult and leads to an increase in manufacturing costs.
JP-A No. 8-332911 relates to a gas generator for an air bag, and discloses in FIG. 19 thereof a device having the following constitution. Due to the existence of a throat portion 162, heated particles generated by an igniter 154 are stored in a first ignition chamber 163 and also introduced into a second ignition chamber 164. In other words, by providing the throat portion 162, the heated particles are injected into a first combustion chamber 155 from the first ignition chamber 163 through a communicating portion 165, whereupon pressure and heat in the second ignition chamber 164 reach predetermined values. Transmission of the pressure and heat into the second ignition chamber 164 are delayed by the throat portion 162, and therefore combustion in a second combustion chamber 156 can be delayed. The delay time is controlled by the size of the throat portion 162.
JP-A No. 8-164816 relates to a gas generator for an air bag, and aims to provide a gas generator of large capacity which is capable of carrying out the stable and even combustion of a gas generating agent having an intense combustion characteristic, such as a non-azide gas generating agent. The structure of the gas generator is disclosed in FIG. 1 and so on.